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Effect of polypropylene fibers and cement on the strength improvement of subgrade lying on expansive soil

Khan, S. Z ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1007/s40996-021-00790-w
  3. Publisher: Springer Science and Business Media Deutschland GmbH , 2022
  4. Abstract:
  5. The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in the soil samples by detecting vibration modes of additives/admixtures components. Unconfined compressive strength tests were conducted on prepared soil samples at three different curing times as 7 days, 14 days, and 28 days. Tests results depicted that unconfined compressive strength was increased due to prolonged curing time and axial strains of expansive soil specimens were reduced accordingly. On the other hand, increase in fiber content induces ductility and increases the residual strains of the soil specimen. It has also been observed that increase in cement content increases the unconfined compressive strength of the expansive soil and reduces the axial strain of the soil specimen. For UCS tests, addition of 6% cement and 0.3% polypropylene fibers by dry weight of soil are found to be the most effective for use in subgrades as it yields greater strength and is rendered economical as well. In case of CBR tests addition of 4% cement and 0.3% PP fibers was found to be most effective as it yielded a CBR value of 18 that is quite higher than the value of raw black cotton soil of Nandipur i.e. 2.7. The optimum combinations of cement and polypropylene fibers to stabilize Nandipur soils have proven to be a unique technique as compared to the other treatment attempts made so far. Applicability of test results in the affected area will definitely help in reducing the expansive nature of Nandipur soils thus advancing towards the sustainable road infrastructure. © 2021, Shiraz University
  6. Keywords:
  7. Black cotton soil ; California Bearing Ratio ; Expansive soil ; Fourier transform infrared (FTIR) analysis ; Polypropylene fibers ; Unconfined compressive strength
  8. Source: Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 46, Issue 1 , 2022 , Pages 343-352 ; 22286160 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s40996-021-00790-w